First Clinical Experience With the Pressure Sensor-Based Autoregulation of Blood Flow in an Artificial Heart

Anatomical and Hemodynamic Characterization of Totally Artificial Hearts

We characterize the anatomy and function of never before studied total artificial hearts (TAHs) using established methods for testing mechanical circulatory support (MCS) devices. A historical review of TAHs is also presented to aid in benchmarking performance metrics. Six TAHs, ranging from spooky Halloween beating hearts to a cute colorful plush heart, were imaged, instrumented (mock flow loops) to measure their pressure, volume, and flow, and qualitatively evaluated by 3rd party cardiac surgeons for anatomical accuracy and surgical considerations. Imaging of Claw, Beating, and Frankenstein TAHs revealed internal motors, circuit boards, and speakers. Gummy TAH was ranked favorite TAH for tactile realism, while Frankenstein TAH had the most favorable audible/visual indicators, including an illuminated Jacob's Ladder. Beating TAH demonstrated superior pulsatile hemodynamic performance compared to Claw TAH (16mL vs 1.3mL stroke volume). Light Up TAH and Gummy TAH functioned only as passive compliance chambers. Cute TAH rapidly exsanguinated due to its porosity (-3.0 L/min flow). These TAHs demonstrated a wide range of anatomical accuracy, surgeon appeal, unique features, and hemodynamic performance. While Claw TAH and Beating TAH successfully generated a modicum of pulsatility, we recommend the clinical community continue to support pre-clinical development of emerging or use of clinically-approved TAHs.

The Future of Durable Mechanical Circulatory Support: Emerging Technological Innovations and Considerations to Enable Evolution of the Field

The field of durable mechanical circulatory support (MCS) has undergone an incredible evolution over the past few decades, resulting in significant improvements in longevity and quality of life for patients with advanced heart failure. Despite these successes, substantial opportunities for further improvements remain, including in pump design and ancillary technology, perioperative and postoperative management, and the overall patient experience. Ideally, durable MCS devices would be fully implantable, automatically controlled, and minimize the need for anticoagulation. Reliable and long-term total artificial hearts for biventricular support would be available; and surgical, perioperative, and postoperative management would be informed by the individual patient phenotype along with computational simulations. In this review, we summarize emerging technological innovations in these areas, focusing primarily on innovations in late preclinical or early clinical phases of study. We highlight important considerations that the MCS community of clinicians, engineers, industry partners, and venture capital investors should consider to sustain the evolution of the field.

Hemocompatibility and biophysical interface of left ventricular assist devices and total artificial hearts

ABSTRACT

Over the past 2 decades, there has been a significant increase in the utilization of long-term mechanical circulatory support (MCS) for the treatment of cardiac failure. Left ventricular assist devices (LVADs) and total artificial hearts (TAHs) have been developed in parallel to serve as bridge-to-transplant and destination therapy solutions. Despite the distinct hemodynamic characteristics introduced by LVADs and TAHs, a comparative evaluation of these devices regarding potential complications in supported patients, has not been undertaken. Such a study could provide valuable insights into the complications associated with these devices. Although MCS has shown substantial clinical benefits, significant complications related to hemocompatibility persist, including thrombosis, recurrent bleeding, and cerebrovascular accidents. This review focuses on the current understanding of hemostasis, specifically thrombotic and bleeding complications, and explores the influence of different shear stress regimens in long-term MCS. Furthermore, the role of endothelial cells in protecting against hemocompatibility-related complications of MCS is discussed. We also compared the diverse mechanisms contributing to the occurrence of hemocompatibility-related complications in currently used LVADs and TAHs. By applying the existing knowledge, we present, for the first time, a comprehensive comparison between long-term MCS options.

Balancing the ventricular outputs of pulsatile total artificial hearts

BACKGROUND

Maintaining balanced left and right cardiac outputs in a total artificial heart (TAH) is challenging due to the need for continuous adaptation to changing hemodynamic conditions. Proper balance in ventricular outputs of the left and right ventricles requires a preload-sensitive response and mechanisms to address the higher volumetric efficiency of the right ventricle.

METHODS

This review provides a comprehensive overview of various methods used to balance left and right ventricular outputs in pulsatile total artificial hearts, categorized based on their actuation mechanism.

RESULTS

Reported strategies include incorporating compliant materials and/or air cushions inside the ventricles, employing active control mechanisms to regulate ventricular filling state, and utilizing various shunts (such as hydraulic or intra-atrial shunts). Furthermore, reducing right ventricular stroke volume compared to the left often serves to balance the ventricular outputs. Individually controlled actuation of both ventricles in a pulsatile TAH seems to be the simplest and most effective way to achieve proper preload sensitivity and left-right output balance. Pneumatically actuated TAHs have the advantage to respond passively to preload changes.

CONCLUSION

Therefore, a pneumatic TAH that comprises two individually actuated ventricles appears to be a more desirable option-both in terms of simplicity and efficacy-to respond to changing hemodynamic conditions.